Process for the purification of sugar-juices.



STATES; PAT NT. oriuca.

CHARLES HIPPOLYTE sna'rn is, or BRUSSELS, BELGIUM, AssiGNoa To STANDARD "SUGAR L rRocEsscoMPANY, LIMITED, OF LONDON NQIAND,

' manner.

rnocsssfiion THE PUaIFicA'uoN oF SU'GhBFJ'ITICfES,

Specification of Letters Patent.

Patented Oct. 13, 1908.

Application filed October 4, 1905. Serial No. 281,327.,

To all whom it mag concern. I

Be it known that 1 CHARLES HIPPOLYTE BERTELS, industriel, a subject of the King of the Belgians, and resident of, 62' Boulevard du Nord, Brussels, Belgium, have invented a certain new and useful Process for tempts have however provedimpracticable,

partly owing to the employment of unsuitable temperature conditions, or improper strength of acid, partly to'the resulting difficulties in filtering, or to the formation of invert sugar, or the neutralization of the solution before filtration, e.;, while the fluo- -si iflfie;is still present, but more particulaa'ly fonaccount of the high co'sts'which'are iasso- I 'ciated with the use of-this acid;

The invention under; consideration con,- sistsflmfan improved'fprocess, byinean'sof which not only is the filtration madeeas" and the/formation of;invert su ar a-Voi'd'e .hut;;the rhyd'rofiuosilicic. acid is: applied in 1 such a way'that it can be recovered for furj ther use,while valuable products (sulfates) I are produced, so that: Cgreat advantages are {obta ned as compare k OWII methods of using.hydrofluosilicic tion of sugar juices.

acid oral y-other substance for the purifica- Froma purely chemical standpoint, the: various 'hases of the process are not yet; thorough y understood, ;but onl by special attention to the following points can a successful result be obtained: 1.1The whole of the operations mustbe; carried out. dccantation must be made at exactly the right moment. 3. Special temperature and acidity conditions as well asexact strengths of acid must be carefully attended to.

The processis carried out in the following The sugar juice, in the form of syrups or molasses, is diluted to 22 Beaum, with ordinary cold water. gives the best precipitate. The liquid is cooled in a water-jacketed vessel by means of cold water to a temperature of 8 C. A temperature of from 8 to 9 C. is the most suitable for a normal precipitation. If the 'with any; of the i 2. The

This density 7 I temperature is higher, the hydrofluosilicic acid fails to act; iflower, the liquid becomes too thick and the precipitate does not form so easily. The jacketed vessel must be provided with a stirrer and distributing apparatus, which. must be easily removable. While the liquid is in the vessel, a sample is taken and analyzed, to determine the ash content. For every gram of ash content 0.514 gram of hyc'n'ofluosilicic acid should be added. Further, it is desirable to add about one tenth more acid than the analysis requires because there are often other constituents present in the syrup which take up a certain quantity of the acid, and without the excess-quantityfmentioned above, some of the potash in the juices mi ht be left unprecipitated. The acid is ad ed in a solution which is in practice a solution of.

about 32 Beaum. As the acid is poured in it must be equally distributed through the liquid by means of the apparatus above re- :ferred to. At the'same time, the stirrer is set in motion and run for about five minutes.

.The stirring and 'distributin apparatus is then removed from the vesse by some suitable arrangements The :liquid being now at rest, the saltsafre precipitated. As soon .as the precipitate has completely settled and the liquid is clear, the latter is decanted either by means of siphons or a row of taps arranged one above the other, the upper one being, of course, openedfirst. must be taken that none of the precipitate, :Which contains the alkali fluosilicate, runs over. Finally the sludge is run off through Great care a tap in the bottom ofthe vessel.

After rinsing once with water the vessel is ready for treating a further quantity of 311106. The precipitateis'caught in a specially arranged vessel and allowed to stand along time so that the Whole of the liquid may be run off after the solid matter has completely settled. The now saltfree liquor is run into a carbonating apparatus to be neutralized with milk of lime, at a density of 20 Baum in order to remove the excess 'of hydrofluosilicic acid. After the addition of milk of lime, the liquid is then warmed to C., and at this temperature it is neutralized, or rather is brought to a slightly alkaline condition as it 'is ractically impossible to exactly neutralize the liquid. The alkalinity per liter will be equivalent to about one tenth of a cubic centimeter of standard lime solution, the liter of which the usual process for the manufacture of is 10 e. cs.:0.05 of CaO (lime), in other words, about .0005 of (19.0 per'liter. The liquid is then heated to 95 or 98 C. and allowed to stand. \Vhen the precipitation is complete it is filtered. From the filter the liquid passes to the vacuum apparatus.

to be condensed and further treated by the ordinary methods employed in sugar factories and refineries. Particular care must be taken not to nontralize the liquid while alkali fluosilicate (potassium fluosilicate) is present, for in this case, if lime or baryta were also present, it would be impossible to recover the hydro lluosilicie acid. As this an expensive item, the value of the process would be greatly decreased if the acid couldonlv he used once. Instead of neutralizing with milk of lime, baryta water of 10 Baum, may be used, so long as it lends itself to the formation of .the products now about to be considered. No excess, however, must be added. Should an excess exist, it may be removed by means of ammonium sulfate.

The process above described can also be employed in the manufacture of sugar by ordinary methods. In this case, the raw (green) juice, either from beet or from the cane, is made up to 22 Baum and is run into lar e coolin vessels for further treatment. t is preferable, however, to apply the processes above described to the syrup obtained after the first defecation (heating and carbonating), for if the greenjuice (i. e. the raw juice before defecation) is treated, thecost of the installation .will be higher, and with no better result. The green juices may also be made more dense, before treatment, by the addition to them of syrup from the first treatment by the acid followed by the carbonating and filtering process, this syrup being already freed from potash. The process allows of the recovery of the hydrofluosilicic acid in a simple way, and therein is its great practical value. In treating the sugar juice, the acid forms an alkaline fluosilicate. In order to recover the acid, it is only necessary to add an equivalent amount of sulfuric acid, and for every 140 parts by weight of sulfuric acid 35 parts by weight of silica, and then to apply heat as in hydrofluosilicic acid. By this means the fluorin is separated from the alkali and hydrofluosilicic acid is again formed. The alkalies are transformed into sulfates and in this way furnish a rich valuable manure. 11 in the recovery process, the addition of silica be on'iitted, then hydrofluoric acid is formed. which may be used for etching and has a high market value. v

llaving thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. The herein described process for puri living sugar juices. which vousists in diluting such juices, adding hydrolluosilieic acid to the diluted juices for precipitating the alkaline salts therefrom, separating theliquor from said precipitate, adding milk of lime to the liquor. heating said liquor and milk of lime. and lilt'ering oil the clear solution.

2. The herein described process for purifying sugar juices, which consists in diluting surh juices, adding hyttlrofluosilicic acid to the diluted juices at a temperature -approxi mately 9 C. for precipitating the alkaline salts therefrom, separating the liquor from said precipitate, adding milk of lime to the liquor, heating said liquor and milk of lime initially to approximately C. and subsequently increasin the tem erature to approximately 95 to 98 and filtering off the clear solution.

3. The herein described process for purifying sugar juices, which consists in diluting such juices to a density of substantially 22 Baum, add-in an excess of hydrofluosilicic acid to the di uted juices at a temperature not above 9 C. for precipitating the alkaline salts therefrom,- decanting the liquor from said precipitate, adding milk of lime to the liquor, heating said liquor and milk of lime initially to approximately 60 C. and subsequently increasing the temperature to approxin'iately 95 C. to 98 C., and filtering off the clear solution.

In witness whereof I have hereunto set my hand in the presence of two Witnesses.

CHARLES llIPPOhI'lH BEIL'IELS.

\Vit'nesses .Iac uus (JiliNElt, (luroolrv lunmx. 

